BRAKE SYSTEM FOR A MOTOR VEHICLE

Description

[0001] The invention relates to a braking system for a motor vehicle for at least four hydraulically actuated wheel brakes with a first electrically actuated pressure source, a second electrically actuated pressure source, an electrically actuated inlet valve for each wheel brake, an electrically actuated outlet valve for each wheel brake and a pressure medium reservoir.

[0002] From WO 2018 / 130483 A1, a braking system with two electrically controlled pressure sources for a motor vehicle with four hydraulically actuated wheel brakes is known. In addition to individually controlled electrical inlet and outlet valves for each wheel, the braking system comprises an electrically controlled circuit separator valve and at least three further electrically controlled valves. The aforementioned components are arranged together in a single unit. Furthermore, two electronic control units are provided, one of which controls the second pressure source and the inlet and outlet valves, while the first pressure source and all other valves are controlled by the other electronic control unit.

[0003] German patent application DE 10 2018 222 478 A1 discloses a braking system comprising two electrically controlled pressure sources, a brake pedal-operated master brake cylinder, individually controlled electrical inlet and outlet valves for each wheel, an electrically controlled circuit isolator valve, an electrically controlled pump valve for the second electrically controlled pressure source, and a normally closed switching valve for the first electrically controlled pressure source. The second electrically controlled pressure source, its associated pump valve, and the inlet and outlet valves are arranged in a second module, while the master brake cylinder with its associated driver isolator valve and simulator, the first electrically controlled pressure source, its associated normally closed switching valve, and the circuit isolator valve are arranged in a first module.

[0004] German patent application DE 10 2019 207088A1 describes a brake system comprising a brake pedal-operated master brake cylinder, a first and a second electrically controlled pressure supply device, and a first brake circuit pressure line section for connection to the first wheel brakes and a second brake circuit pressure line section for connection to the second wheel brakes. The suction side of the second pressure supply device is connected to the first brake pressure line section, and the pressure side is connected to the inlet valves of the associated wheel brakes. A hydraulic connection with an electrically operated drain valve is provided between one of the brake circuit pressure line sections and a pressure fluid reservoir.

[0005] German patent application DE 102017 222445 A1 discloses a brake system comprising a first and a second electrically controlled pressure supply unit. The first pressure supply unit is connected to a brake supply line to which the wheel brakes are connected. A first electrical device controls the first pressure supply unit, and both are assigned to a first electrical partition. A second electrical device controls the second pressure supply unit and the inlet and outlet valves. These are assigned to the second partition.

[0006] German patent application DE 10 2017 216617 A1 describes a brake system with a first electrically controlled pressure source, which is separably connected via a first isolating valve to a first brake circuit supply line, which is connected to two inlet valves. A second electrically controlled pressure source is also described, which is separably connected via a second isolating valve to a second brake circuit supply line, which is connected to two other inlet valves. A circuit isolating device can connect or disconnect the two brake circuit supply lines. A first electronic device actuates the first pressure source and the second isolating valve, and a second electronic device actuates the second pressure source and the first isolating valve.

[0007] It is an object of the present invention to provide an improved braking system suitable for highly automated driving, which in particular offers the highest possible availability necessary for highly automated driving.

[0008] Another objective of the invention is to keep the costs for the manufacture and assembly of the brake system as low as possible.

[0009] This problem is solved according to the invention by a braking system according to claim 1.

[0010] The invention is based on the concept that the braking system comprises a first electrically actuated pressure source, a first electronic control device, a second electrically actuated pressure source, an electrically actuated inlet valve for each wheel brake and an electrically actuated outlet valve for each wheel brake, a second electronic control device, and a hydraulic fluid reservoir, wherein the first pressure source and the second pressure source are connected to a brake supply line to which the at least four inlet valves are connected, wherein an electrically actuated circuit isolating valve is arranged in the brake supply line such that, when the circuit isolating valve is closed, the brake supply line is hydraulically separated into a first line section and a second line section. The first line section is hydraulically connected to the second pressure source and at least two of the at least four inlet valves.Furthermore, the second pipe section is hydraulically connected to the first pressure source and the other, in particular at least two, of the at least four inlet valves. The first electronic control device controls the first pressure source, and the second electronic control device controls the second pressure source and the inlet and outlet valves. The circuit separator valve is also controlled by the second electronic control device.

[0011] In the brake system according to the invention, the first line section thus connects the second pressure source hydraulically to at least two of the at least four inlet valves (first brake circuit) and the second line section connects the first pressure source hydraulically to the other, in particular at least two, of the at least four inlet valves (second brake circuit).

[0012] In the event of a leak in the second brake circuit, the circuit isolating valve controlled by the second electronic control device allows the two brake circuits to be separated by the second electronic control device, and the second electronic control device can build up pressure in at least the first brake circuit or the wheel brakes assigned to the first brake circuit by means of the second pressure source.

[0013] The invention offers the advantage that, through the selection and arrangement of the two electrically actuated pressure sources and the electrically actuated valves in combination with their specific assignment to the two electronic control devices (or the specific electronic partitioning), a separation of the properties of the hydraulic connections into pressureless or non-pressure-resistant (suction) connections and pressure-resistant (pressure) connections is made possible.

[0014] Preferably, it is a pressure medium reservoir at atmospheric pressure.

[0015] Preferably, the (or all) outlet valves are connected to the pressure medium reservoir via a common hydraulic return line.

[0016] Preferably, the circuit isolating valve is designed to be normally open (de-energized), so that during normal braking operation, when the at least four wheel brakes are pressurized by the first pressure source, or in an operating mode when the at least four wheel brakes are pressurized by the second pressure source, no actuation of the circuit isolating valve is necessary. This reduces the power consumption of the braking system and avoids potentially disruptive valve switching noises.

[0017] According to a preferred embodiment of the brake system, when the circuit isolating valve is closed, the second pressure source is hydraulically connected via the first line section to only at least two of the at least four inlet valves, while the first pressure source is hydraulically connected via the second line section to only the other at least two of the at least four inlet valves. This means that when the circuit isolating valve is closed, the brake system is separated or divided into two hydraulic brake circuits, each comprising one of the pressure sources and a different pair of inlet valves. In one (first) brake circuit, the second pressure source is hydraulically connected to at least two of the at least four inlet valves, and in the other (second) brake circuit, the first pressure source is hydraulically connected to the other inlet valves of the at least four inlet valves.In a combined operating mode, the wheel brakes assigned to the first brake circuit can be actuated by means of the second pressure source, while the wheel brakes assigned to the second brake circuit are actuated by means of the first pressure source.

[0018] Preferably, the first pressure source is controlled exclusively by the first electronic control device, or can only be controlled by the first electronic control device. The second pressure source, the inlet and outlet valves, and the circuit separator valve are preferably controlled exclusively by the second electronic control device, or can only be controlled by the second electronic control device.

[0019] Preferably, the braking system comprises a first electrical partition and a second electrical partition, which are electrically independent of each other, wherein the first pressure source and the first electronic control device are assigned to the first electrical partition and the second pressure source, the second electronic control device, the inlet and outlet valves and the circuit separator valve are assigned to the second electrical partition.

[0020] Preferably, the first electronic control device (or the first electrical partition) is supplied by a first electrical power source, and the second electronic control device (or the second electrical partition) is supplied by a second electrical power source, which is independent of the first electrical power source. The first power source is then particularly preferably part of the first electrical partition, and the second power source is part of the second electrical partition.

[0021] According to the invention, the brake system comprises a first assembly in which the first electrically actuated pressure source is arranged, and a second assembly in which the second electrically actuated pressure source, the inlet and outlet valves and the circuit separator valve are arranged.

[0022] According to the invention, the first assembly comprises the first electronic control device and the second assembly comprises the second electronic control device.

[0023] Preferably, the pressure medium reservoir is arranged on the first assembly unit.

[0024] According to a preferred embodiment of the invention, the first and second components are connected to each other by at most one pressure-resistant hydraulic connecting element. The first and second components may be connected to each other by several hydraulic connecting elements; however, at most one—meaning only one—of these hydraulic connecting elements is pressure-resistant, namely the pressure-resistant hydraulic connecting element. Any other hydraulic connecting lines or elements are not pressure-resistant.

[0025] Preferably, the first and second components are connected by a single hydraulic connection element, which is pressure-resistant. Additional, non-pressure-resistant connections / lines, advantageously between the second component and the pressure medium reservoir, are possible.

[0026] A pressure-resistant connecting element or connection is preferably understood to be one that is designed for a maximum operating pressure of one of the pressure sources, in particular the first pressure source, and / or the wheel brakes. Particularly preferably, the pressure-resistant connecting element or connection is designed for a pressure of approximately 180-220 bar. Most preferably, the pressure-resistant connecting element or connection is designed for a pressure of approximately 200 bar.

[0027] Preferably, a non-pressure-resistant connecting element or connection is understood to mean that the connecting element or connection is not designed for the maximum operating pressure of the wheel brakes. Particularly preferably, a non-pressure-resistant connecting element or connection is designed for a maximum pressure of approximately 10 bar.

[0028] Dividing the system into two units offers the advantage over a single-unit design that both units are smaller, lighter, and therefore easier to handle. They can also be manufactured more easily on existing production lines. On the other hand, with a two-unit design, each hydraulic connection between these units results in considerable complexity and expense. It is therefore particularly advantageous to minimize the number of hydraulic connections. Experience has shown that it is beneficial to clearly separate the different functions of hydraulic connections. For example, connections through which hydraulic fluid is drawn in can be designed with the largest possible diameter to minimize hydraulic resistance. It is advantageous if such connections do not need to be pressure-resistant.Conversely, pressure-bearing connections should not have a suction function.

[0029] According to a preferred embodiment of the invention, the first pressure source is connected to the brake supply line, in particular the first section of the brake supply line, via an electrically actuated first isolating valve, wherein the first isolating valve is controlled by the second electronic control device. Thus, by means of the second electronic control device, for example in the event of a failure of the first electronic control device, the first isolating valve can be closed and a flow of hydraulic fluid from the brake supply line towards the first pressure source or first component can be prevented.

[0030] The first isolating valve is preferably designed to be normally open (de-energized). Closing the first isolating valve prevents, for example, in the event of a leak in the first pressure source or the first component, the flow of hydraulic fluid from the brake supply line into the first pressure source or the first component. The first pressure source or the first component can also be hydraulically isolated from the brake supply line by means of the first isolating valve, for example, if the brake system is to be or must be operated in a mode (e.g., in the event of an electrical failure of the first electronic control device) in which the at least four wheel brakes are pressurized by means of the second pressure source.

[0031] The first isolation valve is preferably controlled exclusively by the second electronic control device, or can be controlled exclusively by the second electronic control device.

[0032] The first isolation valve is therefore particularly favorably assigned to the second electrical partition.

[0033] The first isolation valve is preferably arranged in the second assembly unit.

[0034] A check valve opening in the direction of the brake supply line is particularly preferably connected in parallel to the first isolating valve. Advantageously, the check valve is arranged in the second assembly.

[0035] Particularly preferred is a third, electrically actuated, and especially normally closed, is connected in parallel to the first isolating valve and is controlled by the second electronic control device. Advantageously, the third isolating valve is arranged in the second assembly.

[0036] Alternatively, it is preferred that the first isolation valve is controlled by the first electronic control device and, in particular, is arranged in the first assembly unit and is normally closed. In this way, in the event of a leak in the first pressure source, closing the first isolation valve prevents the flow of pressurized fluid from the first pressure source.

[0037] Alternatively, it is preferred that the first pressure source is connected to the brake supply line without the interposition of an electrically actuated valve.

[0038] Preferably, the first pressure source is connected to the hydraulic fluid reservoir via an electrically actuated second isolation valve, the second isolation valve being controlled by the first electronic control device. The second isolation valve is particularly preferably designed to be normally open (de-energized). Through the second isolation valve, hydraulic fluid can flow from the wheel brakes into the hydraulic fluid reservoir, for example, when the brake system is de-energized. This is advantageous for ensuring that the wheel brakes are depressurized (reducing residual braking torque), for example, when the vehicle is parked. A check valve opening towards the first pressure source is particularly preferably connected in parallel to the second isolation valve.

[0039] The second isolation valve is particularly preferably controlled exclusively by the first electronic control device or can be controlled exclusively by the first electronic control device.

[0040] The second isolation valve is therefore preferably assigned to the first electrical partition.

[0041] Preferably, the second isolation valve is arranged in the first assembly unit.

[0042] Preferably, the first pressure source or its pressure chamber, particularly for the purpose of drawing in pressure medium, is connected to the pressure medium reservoir via a check valve opening towards the first pressure source. This check valve is especially preferably provided in addition to the second isolation valve.

[0043] The first assembly preferably comprises at least one first hydraulic connection for connection to the pressure medium reservoir and a second hydraulic connection for connection to the second assembly, wherein the second hydraulic connection is connected to the pressure-resistant hydraulic connecting element. Accordingly, the second hydraulic connection must be designed for a pressure-resistant connection. The first hydraulic connection only needs to be designed for a pressureless (atmospheric) or non-pressure-resistant connection.

[0044] Particularly preferred is the first pressure source, in particular for drawing in pressure medium, connected to the first hydraulic connection via a check valve opening towards the first pressure source, and the first pressure source is connected to the second hydraulic connection, in particular for actuating the at least four wheel brakes.

[0045] According to a preferred embodiment of the invention, the second assembly comprises at least four hydraulic wheel connections for connecting to the wheel brakes, a first hydraulic connection for connecting to the hydraulic fluid reservoir, and a second hydraulic connection for connecting to the first assembly, wherein the second hydraulic connection is connected to the pressure-resistant hydraulic connecting element. Accordingly, the second hydraulic connection of the second assembly is advantageously designed for a pressure-resistant connection. For actuating the wheel brakes, the wheel connections of the second assembly are also designed for a pressure-resistant connection. In contrast, the first hydraulic connection of the second assembly only needs to be designed for a pressureless (atmospheric) or non-pressure-resistant connection.

[0046] Preferably, the second assembly unit does not include any further hydraulic connection besides the wheel connections and the first (atmospheric) and second (pressure-resistant) connection.

[0047] According to a preferred embodiment of the invention, the first hydraulic connection of the first assembly and the first hydraulic connection of the second assembly are connected to different chambers of the pressure medium reservoir. This ensures (at least partial) separation of the pressure medium reservoirs for the first assembly or first pressure source and the second assembly or second pressure source. This results in increased availability of the brake system in the event of a leak.

[0048] Preferably, the first pressure source is formed by a cylinder-piston arrangement with a hydraulic pressure chamber, the piston of which is moved forward by an electromechanical actuator to build up brake pressure and back to reduce brake pressure.

[0049] The first pressure source is preferably formed by a cylinder-piston arrangement with a hydraulic pressure chamber and a pressure port, the piston of which is moved back and forth by an electromechanical actuator. The pressure port is preferably hydraulically connected to the hydraulic fluid reservoir via a check valve opening towards the pressure chamber. The pressure port is also preferably hydraulically connected to the hydraulic fluid reservoir via a second isolation valve. Most preferably, the pressure port is hydraulically connected to the brake supply line, in particular the second section of the brake supply line, via a first isolation valve.

[0050] The first pressure source is preferably formed by a cylinder-piston arrangement with a hydraulic pressure chamber, a suction port, and a pressure port, the piston of which is moved back and forth by an electromechanical actuator. The suction port is preferably hydraulically connected to the hydraulic fluid reservoir via a check valve opening towards the pressure chamber. The pressure port is preferably hydraulically connected to the hydraulic fluid reservoir via a second isolation valve. Most preferably, the pressure port is hydraulically connected to the brake supply line, in particular the second section of the brake supply line, via a first isolation valve.

[0051] The first pressure source is preferably formed by a cylinder-piston arrangement comprising a hydraulic pressure chamber, a suction port, a pressure port, and a vent hole, the piston of which is moved back and forth by an electromechanical actuator. The suction port is particularly preferably hydraulically connected to the hydraulic fluid reservoir via a check valve opening towards the pressure chamber. The vent hole is also particularly preferably hydraulically connected to the hydraulic fluid reservoir. In the case of a cylinder-piston arrangement with a vent hole, a connection between the pressure port and the hydraulic fluid reservoir via a second isolation valve is neither required nor provided. Most preferably, the pressure port is hydraulically connected to the brake supply line, in particular the second section of the brake supply line, via a first isolation valve.

[0052] Preferably, the first pressure source is designed and hydraulically arranged in such a way that it can be controlled to establish a hydraulic connection between the pressure medium reservoir and the brake supply line.

[0053] According to a preferred embodiment of the invention, the second pressure source is designed as a two-circuit or multi-circuit pump. Particularly preferably, the second pressure source is designed as a two-piston pump or a multi-piston pump.

[0054] Preferably, the pressure sides of the two- or multi-circuit pressure source are connected together (to form a common pressure port), and the suction sides of the two- or multi-circuit pressure source are connected together (to form a common suction port). The suction port (and thus the suction sides) is particularly preferably connected to the pressure medium reservoir, especially to the return line of the outlet valves. The pressure port (and thus the pressure sides) is particularly preferably connected to the brake supply line, and most preferably to the first section of the brake supply line.

[0055] Preferably, the braking system comprises no further pressure source besides the first and second pressure sources. Preferably, the braking system comprises neither a further electrically actuated pressure source nor a driver-operated pressure source, such as a master brake cylinder, which is operatively connected to at least one of the wheel brakes for their actuation, e.g., hydraulically or mechanically.

[0056] According to a preferred embodiment of the invention, the braking system comprises an actuating unit for a vehicle driver, wherein the actuating unit is connected to at least one of the two electronic control devices for transmitting a driver request signal and wherein there is no mechanical-hydraulic connection from the actuating unit to the wheel brakes.

[0057] Preferably, the actuation unit comprises a first sensor for detecting a braking request from the driver and a second sensor for detecting a braking request from the driver, which is independent of the first sensor. Preferably, the first sensor is assigned to one of the two electrical partitions and the second sensor is assigned to the other of the two electrical partitions.

[0058] Preferably, the first sensor is connected to one of the two electronic control devices on the signal side, and the second sensor is connected to the other of the two electronic control devices on the signal side.

[0059] The invention offers the advantage that the braking system can maintain the most important residual braking functions even if one of the two redundant electrical pressure sources fails, e.g. due to a failure of its associated electrical power source or electronic control device, or a mechanical fault or leakage in the pressure source itself.

[0060] The braking system according to the invention is therefore particularly suitable for the implementation of highly automated driving functions.

[0061] Further preferred embodiments of the invention will become apparent from the dependent claims and the following description with reference to figures.

[0062] They show schematically Fig. 1 a first embodiment of a brake system according to the invention, Fig. 2 a second embodiment of a brake system according to the invention, Fig. 3 a third embodiment of a brake system according to the invention, Fig. 4 a fourth embodiment of a brake system according to the invention, Fig. 5 a fifth embodiment of a brake system according to the invention, Fig. 6 a further embodiment of a brake system according to the invention, Fig. 7 a further embodiment of a brake system according to the invention and Fig. 8 a further embodiment of a brake system according to the invention.

[0063] In Fig. 1 Figure 1 is a highly schematic representation of a first embodiment of a braking system according to the invention for a motor vehicle. By way of example, the braking system is designed to actuate four hydraulically actuated wheel brakes 8a-8d; expansion to include more wheel brakes is easily possible. By way of example, wheel brakes 8a, 8b are assigned to the rear axle (rear) and wheel brakes 8c, 8d to the front axle (front) of the vehicle.

[0064] The brake system comprises a first electrically actuated pressure source 5, a first electronic control unit 101 (ECU1) which actuates the first pressure source 5, a second electrically actuated pressure source 2, an electrically actuated inlet valve 6a-6d for each wheel brake 8a-8d, and an electrically actuated outlet valve 7a-7d for each wheel brake 8a-8d, and a second electronic control unit 201 (ECU2) which actuates the second pressure source 2 and the inlet and outlet valves 6a-6d and 7a-7d. The brake system also includes a hydraulic fluid reservoir 4. The first pressure source 5 and the second pressure source 2 are connected to a brake supply line 13, to which the four inlet valves 6a-6d are connected.An electrically actuated circuit isolating valve 40 is arranged in the brake supply line 13 such that, when the circuit isolating valve 40 is closed, the brake supply line 13 is hydraulically separated into a first line section 13a and a second line section 13b. The first line section 13a is hydraulically connected to the second pressure source 2 and two of the four inlet valves 6a, 6b, and the second line section 13b is hydraulically connected to the first pressure source 5 and the other two of the four inlet valves 6c, 6d. The circuit isolating valve 40 is controlled by the second electronic control device 201. Advantageously, the circuit isolating valve 40 is designed to be normally open (de-energized).

[0065] The first pressure source 5 and the second pressure source 2 are therefore connected on the pressure side to the brake supply line 13, to which the four inlet valves 6a-6d are connected. Thus, all four wheel brakes 8a-8d can be actuated by means of the first pressure source 5 or by means of the second pressure source 2.

[0066] With the circuit isolating valve 40 closed, the brake supply line 13 is divided into the first line section 13a, to which the inlet valves 6a, 6b and the wheel brakes 8a, 8b are connected, and the second line section 13b, to which the inlet valves 6c, 6d and the wheel brakes 8c, 8d are connected. With the circuit isolating valve 40 closed, the brake system is thus separated or divided into two hydraulic brake circuits, I and II. In the first brake circuit I, the pressure source 2 (via the first line section 13a) is connected only to the wheel brakes 8a and 8b, and in the second brake circuit II, the first pressure source 5 (via the second line section 13b) is connected only to the wheel brakes 8c and 8d. The circuit isolating valve 40 is advantageously designed to be normally open (de-energized).

[0067] The brake system comprises, for example, a first assembly 100, which is designed, for example, as a first electro-hydraulic brake control unit (HECU1) with a valve block HCU1 and the first electronic control device 101 (ECU1), a second assembly 200, which is designed, for example, as a second electro-hydraulic brake control unit (HECU2) with a valve block HCU2 and the second electronic control device 201 (ECU2), and the pressure medium reservoir 4.

[0068] The pressure medium reservoir 4, which is under atmospheric pressure, is advantageously arranged on the first assembly 100. The pressure medium reservoir 4 comprises, for example, two chambers, wherein the first chamber 401 is assigned a first reservoir connection 411 and the second chamber 402 is assigned a second reservoir connection 412.

[0069] The first electrically actuated pressure source 5 is arranged in the first assembly unit 100.

[0070] In the second assembly unit 200, the second electrically actuated pressure source 2 and the wheel-individual brake pressure modulation valves, i.e. inlet and outlet valves 6a-6d, 7a-7d, are arranged.

[0071] As already mentioned, the brake system comprises, for each hydraulically actuated wheel brake 8a-8d, an inlet valve 6a-6d and an outlet valve 7a-7d, which are hydraulically connected in pairs via center connections and each pair is connected to a hydraulic wheel connection 9a-9d, to which the corresponding wheel brake 8a-8d is connected. A check valve 70a-70d, opening towards the brake supply line 13, is connected in parallel to each inlet valve 6a-6d. The outlet connections of the outlet valves 7a-7d are connected via a common return line 14 to a hydraulic connection 62 of the second assembly 200, which is connected to the pressure medium reservoir 4, for example, to its second reservoir connection 412 or to its chamber 402.The inlet ports of all inlet valves 6a-6d can be supplied with pressure via the brake supply line 13 (i.e. with the circuit separator valve 40 open), which is provided by the first pressure source 5 or, e.g. in case of failure of the first pressure source 5, by the second pressure source 2.

[0072] The second electrically controlled pressure source 2 comprises a pressure port 220, which is hydraulically connected to the first line section 13a, and a suction port 221, which is hydraulically connected to the pressure medium reservoir 4, for example via return line 14 and port 62. Port 62, and thus the suction port (the suction side(s)) 221 of the pressure source 2, is, for example, directly connected to the pressure medium reservoir 4 via a line or hose 90. This connection 90 does not carry pressure and can therefore have a large diameter. For example, port 62 is hydraulically connected to the second reservoir port 412 (and thus to the second chamber 402) of the pressure medium reservoir 4 by means of a connecting line / hose 90.

[0073] The first electrically controllable pressure source 5 is designed as a hydraulic cylinder-piston arrangement (or a single-circuit electrohydraulic actuator (linear actuator)), whose piston 36 can be actuated by a schematically indicated electric motor 35 via an interposed rotary-translational transmission 39, in particular by moving it back and forth to build up and release pressure in a pressure chamber 37. The piston 36 defines the pressure chamber 37 of the pressure source 5. A rotor position sensor 44, also only schematically indicated, is provided for controlling the electric motor.

[0074] The first pressure source 5, or rather its pressure chamber 37, is disconnectably connected to the second line section 13b, or the brake supply line 13, via an electrically actuated, preferably normally open, isolating valve 26. The isolating valve 26 is controlled by the second electronic control device 201.

[0075] For example, the pressure chamber 37 of the first electrically controlled pressure source 5 is connected to a system pressure line section 38, by means of which the pressure source 5 is hydraulically connected to a hydraulic port 60 of the first assembly 100, which is hydraulically connected via a hydraulic connecting element 80 to a hydraulic (pressure) port 61 of the second assembly 200. A separating valve 26 is hydraulically arranged between the port 61 and the second line section 13b of the brake supply line 13. The separating valve 26 is advantageously arranged in the second assembly 200.

[0076] Connection 80 represents the only hydraulic pressure connection, in particular the only hydraulic connection, between the first assembly 100 and the second assembly 200. This hydraulic connection transmits brake pressure to actuate the wheel brakes 8a-8d (hence pressure connection). Connection element 80 must therefore be pressure-resistant, e.g., as a pressure-resistant brake hose.

[0077] The first pressure source 5 is connected to the pressure medium reservoir 4 via a check valve 53 opening in the direction of the first pressure source 5.

[0078] For example, pressure chamber 37 is hydraulically connected to a hydraulic connection 63 of the first assembly 100 via a (suction) line 42 (formed in the first assembly 100). Connection 63 is hydraulically connected to the pressure medium reservoir 4, for example to its first reservoir connection 411 and thus to its first chamber 401. The check valve 53, which closes towards the pressure medium reservoir 4, is arranged in the (suction) line 42. The exemplary pressure source / cylinder-piston assembly 5 does not, for example, have any vent holes.

[0079] Furthermore, the first pressure source 5 is connected to the pressure medium reservoir 4 via an electrically actuated, and advantageously normally open, second isolation valve 23. The second isolation valve 23 is controlled by the first electronic control device 101.

[0080] For example, pressure chamber 37 is hydraulically connected to the hydraulic connection 63 (and the (suction) line 42) via the line section 38 and the electrically actuated second isolation valve 23. A check valve 72, opening towards pressure chamber 37, is connected in parallel to the second isolation valve 23.

[0081] In addition to the (pressure medium reservoir) connection 63 and the (pressure) connection 60, the first assembly unit 100 does not include, for example, any further hydraulic connection.

[0082] The second electrically controlled pressure source 2 is, for example, designed as a two-piston pump whose two pressure sides are connected together (to pressure port 220) and whose two suction sides are connected together (to suction port 221). Suction port 221 (and thus the two suction sides) of pressure source 2 is hydraulically connected to the return line 14 and thus to the pressure medium reservoir 4 or to port 62. Pressure port 220 (and thus the two pressure sides) of pressure source 2 are connected to the first line section 13a of the brake supply line 13.

[0083] The brake system includes, for example, a pressure sensor 19 in brake circuit I (pipe section 13a), which is thus assigned to the second pressure source 2. This is advantageous for burst protection when the circuit isolating valve 40 is closed. However, pressure sensor 19 can also be located in brake circuit II, or a second pressure sensor can be provided so that each of the two brake circuits I and II can be directly monitored by means of a pressure sensor.

[0084] For example, the brake system for leakage monitoring includes a level measuring device 50 for determining a pressure medium level in the pressure medium reservoir 4.

[0085] For example, components 5, 53, 23, 72 and line sections 38, 42 are arranged in the first valve block HCU1, and components 2, 6a-6d, 7a-7d, 26, 19 and line sections 13a, 13b (and the line sections between the inlet and outlet valves on the one hand and the wheel connections on the other) are arranged in the second valve block HCU2.

[0086] As already mentioned, each valve block HCU1, HCU2 is assigned one of the electronic control units 101, 201 (ECU1, ECU2). Each electronic control unit 101, 201 comprises electrical and / or electronic elements (e.g., microcontrollers, power components, valve drivers, other electronic components, etc.) for controlling the electrically actuated components of the associated valve block (assembly) and, if applicable, for evaluating the signals from the sensors assigned to this valve block (assembly). Advantageously, the valve block and electronic control unit are designed as an electrohydraulic unit (HECU) in a known manner.

[0087] For the electrical connection, linking and supply of the individual electrical or electrically actuated, controllable, evaluable or similar components of the brake system, a first electrical partition A and a second electrical partition B are provided, which are electrically independent of each other.

[0088] In the figures, those electrical components which are assigned to or belong to the first electrical partition A are marked by an arrow with A, while those electrical components which are assigned to or belong to the second electrical partition B are marked by an arrow with B.

[0089] The electronic control device 101 is assigned to, or belongs to, the first electrical partition A, while the second electronic control device 201 is assigned to, or belongs to, the second electrical partition B. Accordingly, the electronic control device 101 and the second electronic control device 201 are electrically independent.

[0090] To supply the braking system with electrical energy, a first electrical energy source 103, e.g., a vehicle electrical system, and a second electrical energy source 203, e.g., a vehicle electrical system, independent of the first energy source, are provided. The first electrical energy source 103 supplies the first electrical partition A with energy, and the second electrical energy source 203 supplies the second electrical partition B.

[0091] The first electronic control device 101 controls the first pressure source 5. Accordingly, the first pressure source 5 is assigned to or belongs to the first electrical partition A. For example, the first pressure source 5 is supplied with energy (from the first electrical energy source 103) via the first electronic control device 101.

[0092] The second electronic control device 201 controls the second pressure source 2. Accordingly, the second pressure source 2 is assigned to or belongs to the second electrical partition B. For example, the second pressure source 2 is supplied with energy (from the second electrical energy source 203) via the second electronic control device 201.

[0093] For example, the first pressure source 5 can be controlled exclusively by the first electronic control device 101, and the second pressure source 2 exclusively by the second electronic control device 201. In principle, it would be conceivable to equip the electric motor of a pressure source with, for example, two electrically independent motor windings, so that the pressure source could be controlled by the two independent electrical devices. However, this would involve further redundancies, such as duplicate connecting lines, etc., and would therefore be more expensive.

[0094] The remaining components of the brake system are advantageously assigned to either the first electronic control unit 101 (partition A) or the second electronic control unit 201 (partition B). That is, they are controlled or actuated by this control unit and / or supplied with electrical energy and / or are connected to this control unit on the signal side and / or are evaluated by this control unit. To avoid further redundancies, a component is advantageously controllable or actuated, supplied with electrical energy, connected to, or evaluated on the signal side only or exclusively by one of the two electronic control units 101, 201, but not by the other electronic control unit (see the exemplary embodiment for an exception). Fig. 8 with a dual-actuated valve 28).

[0095] The inlet and outlet valves 6a-6d, 7a-7d are assigned to the second electrical partition B and are controlled by the second electronic control device 201. Likewise, the circuit separator valve 40 is assigned to the second electrical partition B and is controlled by the second electronic control device 201.

[0096] The isolating valve 26 for separating the first pressure source 5 and the brake supply line 13 is also, for example, assigned to the second electrical partition B and is controlled by the second electronic control device 201.

[0097] Pressure sensor 19 is also assigned to the second electrical partition B. Its signals are fed to the second electronic control device 201, which evaluates and processes them.

[0098] The isolation valve 23 is assigned to the first electrical partition A and is controlled by the first electronic control device 101.

[0099] Furthermore, the signals from the level measuring device 50 are fed to the first electronic control device 101 and evaluated and processed by it.

[0100] Preferably, the braking system comprises electrically actuated parking brakes on the rear wheels. These are advantageously controlled and actuated by the first electronic control device 101, characterized by A on the wheel brakes 8a, 8b in Fig. 1 .

[0101] The exemplary brake system comprises a primary pressure source 5 and a secondary pressure source 2, each electrically operated by an ECU (Electronic Control Unit) and having a suction port and a pressure port. Brake fluid cannot flow into the pressure port 220 of the secondary pressure source 2, even when de-energized. Preferably, the primary pressure source 5 is a linear actuator with a suction check valve 53, and the secondary pressure source 2 is a piston pump. Preferably, the secondary pressure source 2 can generate a higher pressure than the primary pressure source 5.

[0102] The suction ports 221 and 520 of the two pressure sources 2 and 5 are connected to a pressure medium reservoir 4, preferably each to one of two separate chambers (402, 401).

[0103] The pressure port 521 of the primary pressure source 5 is connected via the electromagnetic valve 26, also called the pressure switching valve, to a primary circuit node (second line section 13b). A check valve 71 can be connected in parallel to the valve 26 (see e.g. Fig. 2 ), which allows a volume flow from the primary pressure source 5 to the primary circuit node (13b).

[0104] The pressure port 220 of the secondary pressure source 2 is directly connected (without the interposition of a valve) to a secondary circuit node (first line section 13a).

[0105] The two circular nodes (pipe sections 13a, 13b) are connected to each other via an electromagnetic valve 40, also called a circular isolation valve.

[0106] The two circuit nodes are connected to wheel brakes 8a-8d via electromagnetic inlet valves 6a-6d, for example the primary circuit node (13b) to the wheel brakes 8c, 8d of the front axle and the secondary circuit node (13a) to the wheel brakes 8a, 8b of the rear axle.

[0107] The wheel brakes 8a-8d are connected to the pressure medium reservoir 4 via electromagnetic outlet valves 7a-7d.

[0108] The output port 521 of the primary pressure source 5 is connected to the pressure medium reservoir 4 via an electromagnetic valve 23, also called a pressure relief valve.

[0109] Preferably, valve 26, valve 40 and valve 23 are designed to be normally open.

[0110] In normal braking operation, the pressure in the wheel brakes 8a-8d is built up by the primary pressure source 5 with the separating valve 23 closed. The pressure is released back into the primary pressure source 5 (retraction of the piston 36) or via the separating valve 23 into the hydraulic fluid reservoir 4.

[0111] The wheel brake pressure is modulated individually for each wheel as needed by the inlet and outlet valves 6a-6d, 7a-7d (e.g., in the case of an anti-lock braking system or other brake control function). If necessary, the isolating valve 26 is closed so that the primary pressure source 5 can draw additional volume from the pressure fluid reservoir 4.

[0112] When a particularly high flow rate is required or requested, both pressure sources 5 and 2 preferably operate simultaneously in parallel. In this case, the pressure reduction occurs at least partially via the isolation valve 23, which is preferably designed as an analog valve, i.e., it can control its flow rate. When a particularly high pressure is requested, the isolation valve 26 is preferably closed, and the secondary pressure source 2 increases the pressure above the pressure of the primary pressure source 5.

[0113] Outside of braking situations, atmospheric pressure equalization is permanently ensured via isolating valve 23 and isolating valve 26.

[0114] In the event of a leak in the brake system, the circuit separating valve 40 is preferably closed, thereby dividing the system into two independent brake circuits I and II.

[0115] Preferably, the isolation valve 23 is controlled by the primary ECU 101. Preferably, the isolation valve 26 is controlled by the secondary ECU 201. The following description of operation in the event of a fault refers to this valve assignment.

[0116] If the primary system (unit 100) experiences an electrical failure, in particular the primary ECU 101 or its power supply 103 (failure of partition A), the secondary ECU 201 closes the isolation valve 26 to build up pressure via the secondary pressure source 2. Pressure is released via the isolation valve 26 or via the outlet valves 7a-7d. Preferably, the inlet and outlet valves are controlled by the secondary ECU 201 (partition B) so that the pressure can be modulated individually for each wheel.

[0117] If the secondary system (unit 200) experiences an electrical failure, in particular the secondary ECU 201 or its power supply 203 (failure of partition B), the pressure is built up and released as in normal operation via the primary pressure source 5 and, if necessary, the isolating valve 23. Individual wheel pressure control is not possible, but a common modulation of the wheel pressures remains possible to prevent the vehicle from being destabilized by wheel lock-up.

[0118] Preferably, the valves are assigned to the two ECUs as described above, the circuit separator valve 40 is controlled by the secondary ECU 201, and the system is divided into two units 100 and 200 with two hydraulic connecting lines, namely the pressure-resistant connecting element 80 and the pressureless or non-pressure-resistant connecting line 90. These two units 100 and 200 preferably each comprise one of the two ECUs, the associated pressure source, and the associated valves.

[0119] In Fig. 2 A second embodiment of a brake system according to the invention is shown schematically. In contrast to the first embodiment of the Fig. 1 A check valve 71 is connected in parallel to the isolating valve 26 of the second assembly 200, allowing a flow of water from the primary pressure source 5 to the line section 13b in order to reduce the hydraulic resistance of the valve 26 in the pressure build-up direction. Furthermore, the pressure sensor 19 is arranged on the line section 13b (brake circuit II).

[0120] In Fig. 3 A third embodiment of a brake system according to the invention is shown schematically. In contrast to the second embodiment of the Fig. 2 In the second assembly unit 200, a further electrically actuated valve 27 is provided, which is normally closed. This valve is connected in parallel to the isolating valve 26. Valve 27 is controlled by the second electronic control device 201.

[0121] In Fig. 4 A fourth embodiment of a braking system according to the invention is shown schematically. In contrast to the braking system of the Fig. 1 The isolating valve 26 has been omitted. The pressure source 5 is directly connected to the first line section 13a.

[0122] However, omitting the isolation valve 26 leads to several disadvantages. If the first unit 100 fails (e.g., due to an electrical fault in ECU1 or Partition A, or due to a leak in unit 100), the pressure source 2 can only build up pressure in the first line section 13a (with the circuit isolation valve 40 closed). The pressure source 5 can only draw in pressure if inlet valves 6c and 6d without check valves 70c and 70d (not shown) are used in the second line section 13b.

[0123] Advantageously, the vehicle axles are therefore reversed in this embodiment, i.e. the second line section 13b is connected to the wheel brakes 8a, 8b of the rear axle and the first line section 13a, which is connected to pressure source 2, is connected to the wheel brakes 8c, 8d of the front axle.

[0124] The electrically operated parking brakes on the rear wheels are advantageously controlled and actuated by the second electronic control device 201 (identified by B on the wheel brakes 8a, 8b in Fig. 4 ).

[0125] In Fig. 5 A fifth embodiment of a braking system according to the invention is shown schematically. In contrast to the braking system of the Fig. 2 The isolating valve 23, including the check valve 72, has been omitted. Therefore, the hydraulic connection with valve 23, 72 between line sections 38 and 42 has been eliminated. Instead, the pressure source 5 now includes an additional mechanism for atmospheric connection. For example, the cylinder-piston assembly 5 (linear actuator) is designed with a vent hole 522.

[0126] A corresponding design (omission of valves 23, 72 and design of the pressure source 5 with vent hole 522) is also found in the brake systems of the exemplary embodiments of the Fig. 1 , 3 , 4 possible.

[0127] The elimination of the isolating valve 23 therefore leads to additional effort in the pressure source 5. The function of the isolating valve 23 described above, namely to reduce the additional volume provided by the pressure source 2, must now be taken over by the outlet valves 7a-7d, which is less convenient.

[0128] According to further preferred embodiments of the braking system according to the invention (see e.g. Fig. 6 and 7The second pressure source 2 is designed as a dual-circuit system, specifically as a two-piston pump. The two suction sides remain connected (suction port 221) and are connected to the return line 14. The two pressure sides are not connected together. One of the pressure sides (pressure port 232) is connected to the first line section 13a, and the other pressure side (pressure port 233) is connected to the second line section 13b. This design of the pressure source 2 is possible in all previously described embodiments. This design has the advantage that dual-circuit operation is possible even after a failure of the first partition A (e.g., the first electronic control device 101), meaning that both line sections 13a and 13b can be pressurized by means of the pressure source 2. A disadvantage is the reduced pressure build-up dynamics in line section 13a during dual-circuit operation. Examples are given in Fig. 6 and 7corresponding exemplary embodiments starting from the braking systems of the Fig. 3 and 5 depicted.

[0129] In Fig. 8 A further embodiment of a braking system according to the invention is shown. The differences to the first embodiment of the Fig. 1 are described below.

[0130] The first assembly 100 (or valve block HCU1) comprises, in addition to the first pressure source 5 and its (suction) line 42 with the check valve 53, a normally closed isolating valve 26, which is controlled by the first electronic control device 101. The hydraulic connection with the valves 23, 72 between line section 38 and 42 is omitted, and the pressure source 5 does not include any vent holes. The isolating valve 26 is hydraulically arranged between the pressure source 5 and line section 13b of the brake supply line 13, specifically between the pressure source 5 and the connection 60 of the first assembly 100.

[0131] The second assembly 200 (or valve block HCU2) comprises, in addition to the second pressure source 2 and the inlet and outlet valves 6a-6d, 7a-7d and the circuit separator valve 40, which are controlled by the second electronic control device 201, a normally open isolating valve 28, which is connected in parallel to the pressure source 2, i.e., it connects the suction sides of the pressure source 2 with the pressure sides of the pressure source 2 or connects the return line 14 with the line section 13a. The isolating valve 28 is a check valve 29 connected in parallel with the isolating valve 29, which closes towards the pressure medium reservoir 4 (the return line 14). The isolating valve 28 is preferably designed as an analog valve. The isolating valve 28 is designed to be actuated by two different actuators, i.e.,It comprises two separate, electrically independent actuating coils, one coil being controlled by the first electronic control device 101 (Partition A) and the other coil being controlled by the second electronic control device 201 (Partition B).

[0132] The selection and arrangement of the electrically actuated valves, the electronic partitioning, and in particular the allocation between electrically actuated valves and electronic control devices enable high availability of the brake system while simultaneously allowing for an advantageous arrangement of the brake system components in two electro-hydraulic brake control units, HECU1 and HECU2. This design allows the two brake control units, HECU1 and HECU2, to require only one pressure-tight connection to the hydraulic fluid reservoir, in addition to the pressureless or non-pressure-resistant connections. The at least four connections between the second assembly 200 (or the wheel connections (9a-9d)) and the wheel brakes 8a-8d are also pressure-tight.

[0133] Dividing the brake control system into two units, HECU1 and HECU2, offers the advantage over a single unit that both units are smaller, lighter, and therefore easier to handle. They can also be manufactured more easily on existing production lines. However, with two separate units, each hydraulic connection between them introduces additional complexity and costs. Therefore, it is advantageous to minimize the number of hydraulic connections. Furthermore, it is beneficial to clearly separate the different functions of hydraulic connections. Connections that draw in hydraulic fluid should have the lowest possible hydraulic resistance and therefore the largest possible diameter. To achieve this, it is advantageous if such connections do not need to be pressure-resistant.Conversely, pressure-bearing connections should not have a suction function.

Claims

1. A brake system for a motor vehicle for at least four hydraulically actuatable wheel brakes (8a-8d), said brake system comprising a first electrically actuatable pressure source (5), a first electronic control device (101), a second electrically actuatable pressure source (2), an electrically actuatable inlet valve (6a-6d) for each wheel brake and an electrically actuatable outlet valve (7a-7d) for each wheel brake, a second electronic control device (201), and a pressure medium reservoir (4), wherein the first pressure source (5) and the second pressure source (2) are connected to a brake supply line (13) to which the at least four inlet valves (6a-6d) are connected, wherein an electrically actuatable circuit separating valve (40) is arranged in the brake supply line (13) in such a manner that, when the circuit separating valve (40) is closed, the brake supply line (13) is hydraulically separated into a first line section (13a) and a second line section (13b), wherein the first line section (13a) is hydraulically connected to the second pressure source (2) and at least two of the at least four inlet valves (6a, 6b), and the second line section (13b) is hydraulically connected to the first pressure source (5) and the other, in particular at least two, of the at least four inlet valves (6c, 6d), wherein the first electronic control device (101) controls the first pressure source (5), the second electronic control device (201) controls the second pressure source (2) and the inlet and outlet valves (6a-6d, 7a-7d), and the circuit separating valve (40) are controlled by the second electronic control device (201), characterized by a first structural unit (100) in which the first electrically actuatable pressure source (5) is arranged and which comprises the first electronic control device (101), and a second structural unit (200) in which the second electrically actuatable pressure source (2), the electrically actuatable inlet and outlet valves (6a-6d, 7a-7d), and the circuit separating valve (40) are arranged and which comprises the second electronic control device (201).

2. The brake system as claimed in claim 1, characterized in that a first electrical partition (A) and a second electrical partition (B) are provided, which are electrically independent of one another, wherein the first pressure source (5) and the first electronic control device (101) are assigned to the first electrical partition (A) and the second pressure source (2), the second electronic control device (201), the inlet and outlet valves (6a-6d, 7a-7d) and the circuit separating valve (40) are assigned to the second electrical partition (B).

3. The brake system as claimed in claim 1 or 2, characterized in that the first pressure source (5) is controlled exclusively by the first electronic control device (101) and the second pressure source (2), the inlet and outlet valves (6a-6d, 7a-7d) and the circuit separating valve (40) are controlled exclusively by the second electronic control device (201).

4. The brake system as claimed in claim 3, characterized in that the first structural unit (100) and the second structural unit (200) are connected to one another by at most one pressure-resistant hydraulic connecting element (80).

5. The brake system as claimed in claim 3 or 4, characterized in that the first structural unit (100) and the second structural unit (200) are connected to one another by only one hydraulic connecting element (80), wherein said connecting element is designed to be pressure-resistant.

6. The brake system as claimed in any one of the preceding claims, characterized in that the first pressure source (5) is connected to the brake supply line (13) via an electrically actuatable first separating valve (26), wherein the separating valve (26) is controlled by the second electronic control device (201).

7. The brake system as claimed in claim 6, characterized in that the first separating valve (26) is designed to be normally open.

8. The brake system as claimed in any one of the preceding claims, characterized in that the first pressure source (5) is connected to the pressure medium reservoir (4) via an electrically actuatable second separating valve (23), wherein the second separating valve (23) is controlled by the first electronic control device (101).

9. The brake system as claimed in claim 8, characterized in that the second separating valve (23) is designed to be normally open.

10. The brake system as claimed in any one of the preceding claims, characterized in that the first pressure source (5) is connected to the pressure medium reservoir (4) via a check valve (53) which opens in the direction of the first pressure source (5).

11. The brake system as claimed in any one of the preceding claims, characterized in that, in addition to the first and second pressure sources (2, 5), the brake system does not comprise a further pressure source for building up a brake pressure for actuating the wheel brakes.

12. The brake system as claimed in any one of the preceding claims, characterized by an actuating unit for a vehicle operator, wherein the actuating unit is connected to at least one electronic control device (101, 201) for transmitting a driver demand signal, and wherein there is no mechanical-hydraulic connection from the actuating unit to the wheel brakes.